Tuesday, 28 January 2014
A guilty passion for this flower
I don't know how many passion flowers there were on the Passionflower erupting from our back fence but on one evening last month I estimated 1500 buds with a dozen open that day. There are less buds and flowers now, particularly after our first summer heat waves. Each flower opens in the morning and closes, for good, sometime in the middle of the night (I haven't got up to check exactly when).
It's the invasive Passiflora caerulea (Blue Passionflower) from South America, probably the rootstock of a now departed Edible Passionflower or Passionfruit, Passiflora edulis (the Romans among you will notice the scientific and common names match pretty well this case). Beautiful flowers and edible, but not as desirable, fruits. The plant had already captured our back fence when we arrived in the house, and as tenants we haven't felt it within our remit to do more than restrict it's advance a little.
So with guilt, apathy and the law on our side, we have been enjoying those gorgeous flowers. It's been a chance to look at them more closely and to marvel, as always, at the mechanics of their innards.
I'm not going to explain how the bits and pieces of the flower are responsible for its generic common name, the Passionflower - Wikipedia does that well enough. Suffice it to say, as they say, Christians have found holy lances, whips, apostles, a crown of thorns, nails and wounds from the crucifixion cross and perhaps even the Holy Grail in a single flower.
Perhaps more informatively, the flower is a great way to understand how a flower works. In this case it's set up with big bold structures to suite larger bees, like bumblebees. Once you get past the frilly outside and target-like colouring, the next most obvious feature is the androgynophore.
For non-Roman readers, that translates as the male-female-column.That is, the combined structure formed by five boy bits (stamens) and three girl bits (styles). The thing you notice about the styles are the pairs of eye-like receptive areas (stigmas) on each of the purple stalks. The stamens have a greenish 'filament' with foot-like anthers pivoting on their ends.
The short purple fringe sticking inwards is involved in nectar production, while the outward spreading purple and white fringe is presumably all about attracting big bees to the flower in the first place. Bubblebees buzz and bump into more of the beckoning bits; our local honey bees barely brush against the dangling anthers, so no (bland) fruit for us.
The five petals and five sepals (the latter usually a layer of flower parts outside the petals, and often green) form an even ring of 10 pretty petal-like parts - although the sepals do have a tiny green hook on their back (which you can just see in this picture also showing a spring-like tendril dangling over the flower from the climbing stem).
Want to know more? St Louis' Missouri Botanical Garden reckon there are 520 species of Passiflora with plenty more still to be described, and you can catch up with their latest passionate research at Passiflora Research Network. For some cute pictures of the flower close-up see this Mic-UK site.